Recently, a secondary battery, which can be charged and discharged, has been widely used as an energy source for wireless mobile devices. Also, the secondary battery has attracted considerable attention as a power source for electric vehicles (EV), hybrid electric vehicles (HEV), and plug-in hybrid electric vehicles (Plug-in HEV), which have been developed to solve problems, such as air pollution, caused by existing gasoline and diesel vehicles using fossil fuels.
Small-sized mobile devices use one or several battery cells for each device. On the other hand, middle or large-sized devices, such as vehicles, use a middle or large-sized battery module having a plurality of battery cells electrically connected to one another because high power and large capacity are necessary for the middle or large-sized devices.
Generally, a plurality of unit cells are mounted in a cartridge which connects the unit cells in series and/or in parallel to each other, and a plurality of cartridges are electrically connected to each other, thereby manufacturing a battery module. According to circumstances, two or more battery modules are electrically connected to each other, thereby manufacturing a middle or large-sized battery pack or system providing higher power.
Meanwhile, such a middle or large-sized battery pack exhibits high safety with respect to deformation of the battery pack in the thickness thereof but low safety with respect to deformation of the battery pack in the electrode terminal direction of the battery cells.
In particular, in a case in which a plurality of battery cells is electrically connected in series to each other as in a middle or large-sized battery pack, a short circuit occurs at electrode terminal regions of a battery module when external force caused due to, for example, vehicle collision is applied to the battery pack with the result the battery pack may catch fire or explode.
Consequently, there is a high necessity for a middle or large-sized battery pack including an electrode terminal connecting device that is capable of shutting off an electrode terminal connection region of a battery module through a simple structure when external force is applied to the battery pack, thereby fundamentally solving the above problems.